Freddy Rumsen is a senior copywriter at Sterling Cooper who was forced to take a leave of absence after drunkenly urinating in his pants and then passing out right before an important meeting with the Samsonite luggage representatives. He has been with Sterling Cooper since the days when Roger Sterling's father was in charge, and has considerable tenure - thus the leave of absence vs. being fired.

While leading a brainstorming session for the Belle Jolie lipstick account, he remarks on Peggy's copywriting prowess and sings her praises to Don. When Freddy is forced to go on leave, it is his office that Peggy is given.

Freddy Returns

A year after Sterling Cooper Draper Pryce opened its doors, Freddy returned to the office with the promise of a 2 million dollar account. His one stipulation is that he does not want Pete Campbell involved with the account. Freddy is also clean and sober, as well as being an AA sponsor. Increasingly annoyed by his old-fashioned attitudes and opinions while working with him, Peggy snaps at him. He does not attend the company Christmas party, though his reasons are more due to the presence of alcohol and the temptation to drink again than Peggy's insult.[1]

Season Seven opens with Freddie Rumsen, now freelancing, delivering an outstanding pitch to Peggy. It turns out that he is a frontman for Don. Also in Season Seven, he encourages Don to stop drinking.

Personality

Freddy has been shown playing Mozart’s "Eine Kleine Nachtmusik" with his pants zipper.

Peggy called him out for being old fashioned in his thinking particularly where it concerns women.

The final straw and catalyst to his "leave of absence" occurred when he was so drunk at the office that he seemed to black out and urinate on himself.